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Date:   Mon, 31 Jan 2022 19:58:14 +0100
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From:   Jan Kiszka <jan.kiszka@siemens.com>
Subject: [PATCH] ipheth: fix EOVERFLOW in ipheth_rcvbulk_callback
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To:     Jakub Kicinski <kuba@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Georgi Valkov <gvalkov@abv.bg>
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        Linux Netdev List <netdev@vger.kernel.org>,
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From: Georgi Valkov <gvalkov@abv.bg>

When rx_buf is allocated we need to account for IPHETH_IP_ALIGN,
which reduces the usable size by 2 bytes. Otherwise we have 1512
bytes usable instead of 1514, and if we receive more than 1512
bytes, ipheth_rcvbulk_callback is called with status -EOVERFLOW,
after which the driver malfunctiones and all communication stops.

Resolves ipheth 2-1:4.2: ipheth_rcvbulk_callback: urb status: -75

Fixes: f33d9e2b48a3 ("usbnet: ipheth: fix connectivity with iOS 14")
Signed-off-by: Georgi Valkov <gvalkov@abv.bg>
Tested-by: Jan Kiszka <jan.kiszka@siemens.com>
---
  drivers/net/usb/ipheth.c | 6 +++---
  1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/usb/ipheth.c b/drivers/net/usb/ipheth.c
index cd33955df0b6..6a769df0b421 100644
--- a/drivers/net/usb/ipheth.c
+++ b/drivers/net/usb/ipheth.c
@@ -121,7 +121,7 @@ static int ipheth_alloc_urbs(struct ipheth_device *iphone)
  	if (tx_buf == NULL)
  		goto free_rx_urb;
  
-	rx_buf = usb_alloc_coherent(iphone->udev, IPHETH_BUF_SIZE,
+	rx_buf = usb_alloc_coherent(iphone->udev, IPHETH_BUF_SIZE + IPHETH_IP_ALIGN,
  				    GFP_KERNEL, &rx_urb->transfer_dma);
  	if (rx_buf == NULL)
  		goto free_tx_buf;
@@ -146,7 +146,7 @@ static int ipheth_alloc_urbs(struct ipheth_device *iphone)
  
  static void ipheth_free_urbs(struct ipheth_device *iphone)
  {
-	usb_free_coherent(iphone->udev, IPHETH_BUF_SIZE, iphone->rx_buf,
+	usb_free_coherent(iphone->udev, IPHETH_BUF_SIZE + IPHETH_IP_ALIGN, iphone->rx_buf,
  			  iphone->rx_urb->transfer_dma);
  	usb_free_coherent(iphone->udev, IPHETH_BUF_SIZE, iphone->tx_buf,
  			  iphone->tx_urb->transfer_dma);
@@ -317,7 +317,7 @@ static int ipheth_rx_submit(struct ipheth_device *dev, gfp_t mem_flags)
  
  	usb_fill_bulk_urb(dev->rx_urb, udev,
  			  usb_rcvbulkpipe(udev, dev->bulk_in),
-			  dev->rx_buf, IPHETH_BUF_SIZE,
+			  dev->rx_buf, IPHETH_BUF_SIZE + IPHETH_IP_ALIGN,
  			  ipheth_rcvbulk_callback,
  			  dev);
  	dev->rx_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
-- 
2.34.1